/**
 * #      543
 * 名称   二叉树的直径
 * 链接   https://leetcode-cn.com/problems/diameter-of-binary-tree
 * 题解   [982](https://leetcode-cn.com/problems/diameter-of-binary-tree/solution)
 * 通过率 52.8%
 * 难道   简单
 */

